Litter boxes are common devices used for the collection and easy disposal of cat waste. The litter used in the litter boxes is commonly comprised of a granulated material that clumps within a short time period after a cat excretes into it. The owner can then scoop up these clumps and safely dispose of them. Self cleaning litter boxes are designed to automatically move the waste from the litter box into a waste receptacle. One system and mechanism for moving the clumps involves a motor driven rake made of a plurality of rake tines that, upon activation, sift through the litter pan to carry or push the litter clumps upward along an inclined ramp from where they fall into the receptacle. After the litter clumps have been deposited inside the waste receptacle, the motor stops and reverses direction to return the rake to the back of the litter box. Some litter box models are equipped with sensors that detect a cat's presence in the litter box and activate the rake motor as soon as the cat leaves the box. Litter granules are typically maintained at a depth of at least 1-2 inches. The main ingredient in the litter granules is sodium bentonite which is a special type of clay that uses the moisture it absorbs to bond soiled litter particles into clumps for easy removal and disposal. Odor containing chemicals are also often incorporated into the litter. Other clumping litters are made of organic products like corn, pine and wheat.
The waste collection system for Littermaid® litter boxes, a known brand currently on the market, comprises a litter box container that contains the litter, a rake that moves the waste toward the waste receptacle, a ramp leading to the waste receptacle, a short interface junction that bridges between the top of the ramp to the top of the waste receptacle, and the waste receptacle itself. In the Littermaid® unit, the waste receptacle is attached to the interface junction and accumulates waste. When filled, the waste receptacle needs to be removed and the waste discarded. Removing the receptacle as designed is time consuming, cumbersome and requires contact with waste material. One solution to this problem found in the prior art is the use of inserts or disposable liners that receive the waste moved by the rakes from the litter pan. The inserts are reusable and can easily be removed, emptied and replaced. After a period of use, the inserts are disposed of and replaced with new ones.
The prior art references describe various automatic and self cleaning litter box features, embodiments and methods for cleaning the litter boxes. For example, some automatic litter box waste receptacles disclosed in the art are equipped with lids designed to open as the rake approaches the top of the litter pan and close as the rake retreats. In another reference, a box within a box device is utilized to change litter without having to touch or manipulate the soiled litter. Waste receptacle inserts are also referred to in several of these references. U.S. Pat. No. 5,048,465 discloses a self-cleaning kitty litter box and method for cleaning the litter box. The kitty litter box has a removable pan in which kitty litter is placed. A motor and timing device are provided for periodically moving a rake through the kitty litter so to push solid waste to one end of the pan. The rake is then rotated in contact with a stop out of the pan and the rake then moves forward and drops the collected solid waste into a storage tray. The motor and timer allow this process to be periodically repeated without involvement of the cat owner until ultimate disposal of the cat waste is desired. U.S. Pat. No. 6,848,394 describes a cat litter box which will allow cat owners to change litter without having to touch or manipulate the soiled litter. The device consists of a box within a box. The inside box is made with swinging trap doors on the bottom of the interior part of a shell of the device. This allows the cat litter to flow freely from the interior shell to the bottom half of the exterior shell. U.S. Pat. No. 6,851,386 is directed to a waste box for use with a litter box where the waste box is used for collecting litter clumps removed from the litter box and for collecting litter particulate scattered onto the waste box after a cat exists the litter box. U.S. Pat. No. 6,951,190 discloses a self-cleaning litter box having a base, a litter pan, an upper hood and a lower hood. A rake is used to sweep litter clumps disposed in the litter pan and into a waste box. The rake is inserted and removed without the use of tools in order to clean or replace the rake. Liners inside the litter pan and waste box allow for easy cleaning. Sensors detect the presence of a cat inside the litter pan. Upon exit, an actuator receives an output signal for actuating the drive assembly. After a predetermined time delay after receipt of the output signal, the raking cycle commences. U.S. Pat. No. 6,298,808 teaches a plurality of modules to guard the privacy of the cat. The privacy system includes a stackable module, including a frame, a cantilevered platform with a first end attached to the frame and a second free end that extends away from the frame and/or a fastener to attach the modules to one another. Each module includes an opening to allow for access by a cat into the interior of the module. The modules may be stacked one on top of the other and then fastened together in a manner that prevents vertical motion between the modules. U.S. Pat. No. 6,378,461 relates to a self-cleaning litter box for cats that employs a comb drive to drive a comb through litter to remove waste from the litter. A sensor for detecting the presence of an obstruction is coupled to the comb drive and stops the comb drive upon detecting an obstruction. A removable tray for cat litter may be provided. The tray may be disposable. A pivotable ramp facilitates ingress to, and egress from, the litter box. The ramp may be carpeted. A tray receives the litter box and a hood encloses the litter box to provide privacy. U.S. Pat. No. 7,051,678 is for an enclosed litter box having a slidably removable litter tray and an integral rake. The litter box includes an enclosure with an arched top having a compound curved surface. The exterior of the enclosure may be decorated with various motifs.
Problems in the Littermaid® style self cleaning litter box and similar systems not addressed in the prior art or in the self cleaning litter boxes currently on the market are 1) the tendency for waste build-up at the interface junction along the top of the ramp and the waste receptacle, 2) the tendency for waste to fall in the gap between the waste receptacle and the disposable insert, 3) maintenance and handling of receptacles in the proximity of soiled litter and waste and 4) costly and careless disposal of plastic waste receptacles.